1. Field of the Invention
The present invention relates to an apparatus for controlling a warp tensioner and to a weaving machine with such an apparatus
2. Description of the Prior Art
It is known that every weaving machine is provided with a warp tensioner. The warp tensioner has a tensioner beam which is always held in the same central position. The warp tensioner performs the following tasks, among others:
Compensation of the warp thread length during the formation of the shed, and PA1 Production of the warp tensile force and thus of the warp tension via the tensioner beam.
It is also known that the warp tension is dependent on the type of cloth.
An apparatus of the initially named kind is known from DE-U-93 04 801.7. In this apparatus the pivotally journalled tensioner beam is monitored by means of a position sensor and subjected to a bias force by an air spring. A control valve is associated with the air spring in order to vary the tension in the warp through a variation of the air pressure, with the warp tension being proportional to the change of the air pressure. The air spring has a predetermined spring characteristic and can thus only be used within limits. This applies even if the warp tensioner is subject to a bias tension by means of coil springs or torsion bars.
This is a disadvantage which leads to the requirement of replacing the tensioning springs when the article is changed, which has the resultant and known disadvantages.
The invention will be explained in the following with reference to the accompanying drawings.